Kaposi's Sarcoma in the setting of the acquired immunodeficiency syndrome (AIDS) is a life threatening disorder which has taken on epidemic proportions in the United States over the past 2 years. This proposal seeks to establish effective therapy for this malignancy and to better understand the immune abnormalities underlying this devastating disease. A randomized, prospective clinical study comparing the efficacy toxicity, and immune modulating capabilities of the chemotherapeutic agent, etoposide (VP16-213) versus human recombinant alpha interferon will be conducted. Stratification will be by extent of disease. The incidence of infection as well as the antitumor and immune effects of these agents will be evaluated. In addition a feasibility study of the usefulness of high dose chemotherapy and radiation followed by bone marrow transplantation from an immunologically normal sibling donor will be assessed in a series of sequential studies aimed at determining the effectiveness of this modality of treating Kaposi's sarcoma and for restoring normal immunity without excessive toxicity or infectious complications. Finally, the growth and immunologic characteristics of T-lymphocyte progenitors (CFU-TL) will be investigated in patients with AIDS and/or Kaposi's sarcoma as a means of establishing whether intrinsic or acquired abnormality of T cell maturation is responsible for the severe immunodeficiency seen in these patients. We will also assess whether this assay may be a useful prognostic indicator of response to therapy for Kaposi's sarcoma.